I *think* the light brown hakama are reserved for heads of the style, kancho I think its called?
As for being dead, funny story. the senior student of my dojo was telling me at his first seminar when he was white belt, just beginning, he had his gi right over left. The teacher of the seminar walks up with a smile on his on his face and says "You are dead." and walks away. Thought that was pretty comical.
Actually dark grey hakama does exist, evenly i saw a Yoshinkan instructor wear such color of hakama.